Identification of enterotoxigenic staphylococci from sheep and sheep cheese

The total of 127 Staphylococcus aureus strains obtained from sheep and sheep cheese were examined for their biochemical activities, biotypes, phage patterns, and ability to produce enterotoxins. Of the 83 staphylococcal strains isolated from animals 77 (93%) were classified as the C biotype. Of this group of sheep-adapted strains, 61 (79%) were sensitive to phage 78, and 46 (60%) produced enterotoxin C exclusively. The three isolated belonging to the A biotype produced enterotoxin D, and two of the three unclassifiable strains produced enterotoxin A. Of the 44 staphylococcal strains isolated from sheep cheese, there were 37 (84%) identified as the C biotype. From this series, 31 (84%) strains were lysed with phage 78, 6 (16%) strains produced enterotoxin C, and 1 strain produced enterotoxin A. One of the six strains determined as the A biotype produced enterotoxin D. C biotype strains, especially of ovine origin, are an exception among animal staphylococci, because a large number of them are enterotoixgenic. The C antigenic type is the most usual of the known enterotoxins in staphylococci of animal provenance.     

湖羊、同羊12个同工酶座位的检测

Gene frequencies of Hu sheep and Tong sheep were obtained with “Random sampling in typical colonies of a central area“.of the 12 loci tested in Hu shpee.11 loci were polymorphic.Reliability of the estimated frequencies of 27 alleles reached 0.95 except for Po^F,Tf^A,Tfd,Hb-β^A and CAF which had reliabilities of 0.5222,0.7478,0.5222,0.6212 and 0.899,respectively,Of the 12 loci tested in Tong sheep,11 loci were polymorphic.Reliability of the estimated frequency of 25 alleles reached 0.95 except for Tf^A,Tf^E and CAF which had reliabilities of 0.931,0.6922 and 0.7924,respectively.The average heterozygosity(H) and average homozygosity(J) was computed and the J of the two sheep colonies was 0.6619 and 0.6448,respectively.Consistent with our conclusions based on genetic data,previous research divided the native sheep populations of East and South Central Asia into three group:the “mongolian group“ “south-Asian group“and “European group“ .Consequently,the degree of genetic similarity between populations and known groups would seem to provide a reliable means of determining the genetic relationships between populations and may reflect the true genetic origin of Hu sheep and Tong sheep in China.     

A novel sheep gene,MMP7, differentially expressed in muscles from black-boned sheep and local common sheep

Differences in gene expression in muscles from Chinese black-boned sheep and local common sheep were investigated using mRNA differential display. One differentially expressed novel gene was identified through semi-quantitative RT-PCR, and the full-length cDNA sequence was then obtained using the rapid amplification of cDNA ends (RACE). The nucleotide sequence of this gene is not homologous to any of the known sheep genes, but it contains an open reading frame encoding a protein of 416 amino acids, which has high homology with matrix metallopeptidase 7 (matrilysin, uterine) (MMP7) of 10 species: bovine (93%), rhesus monkey (75%), human (74%), pig (73%), chimpanzee (73%), dog (73%), horse (72%), mouse (66%), rat (65%), and chicken (53%). Thus the novel gene can be defined as the sheepMMP7 gene. It was finally assigned to GeneID: 100192317. The phylogenetic tree analysis revealed that the sheepMMP7 gene is closely related to the bovineMMP7. Our experiment is the first one to establish the primary foundation for further research on the sheepMMP7 gene.     

Population response of reintroduced bighorn sheep after observed commingling with domestic sheep

Bighorn sheep (Ovis canadensis) often die from respiratory disease after commingling with domestic sheep. From 2000 to 2009, we observed commingling between domestic and reintroduced bighorn sheep in 3 populations in UT, USA. We investigated how commingling affected survival of radio-collared female bighorns that were released initially (founder) and those that were subsequently released (augmented). We predicted that the proportion of young surviving to their first winter and population growth would be lower after observed commingling with domestic sheep. We observed groups of bighorns year-round on 2,712 occasions and commingling between domestic sheep and bighorns in 6 instances. On Mount Timpanogos, survival rates were best modeled as constant for females (n?=?57) before and after observed commingling with domestic sheep. Survival rates of female bighorns, however, decreased significantly in Rock Canyon (n?=?21) and on Mount Nebo (n?=?22) for founder, but not augmented bighorns after observed commingling with domestic sheep. Also, the proportion of young surviving to their first winter was almost 3 times lower and population growth was reduced for bighorns after observed commingling with domestic sheep in Rock Canyon and on Mount Nebo. Commingling between domestic and bighorn sheep reduced population parameters in 2 of 3 bighorn populations we studied; however, on Mount Timpanogos, interactions between those 2 species were not fatal for radio-collared female bighorns. Wildlife biologists should manage for spatial separation of these 2 species and consider the location of hobby farms and trailing operations of domestic sheep near release sites for bighorns.     

Intermittent tracheostomy in sheep

A modified tracheostomy was designed for respiratory function studies in sheep. Our primary objective was to prevent development of severe tracheal stenosis, which was observed with procedures designed for canine tracheostomy. Surgery consisted of an intercartilaginous tracheal slit, with apposition of tracheal mucosa to skin. This procedure produced no significant stenosis at postmortem evaluation in 19 sheep. In contrast, 5 of 20 sheep with excision of the ventral 1/3 of the third and fourth tracheal rings, had severe tracheal stenosis.     

Clinical examination of sheep

Clinical examination of sheep involves the interpretation of information about both the individual and the flock within the context of the farm environment. It is an art, which relies on careful observation and the systematic collection of specific data, suggestions of which are presented in tabular format. However, interpretation is subjective with the potential for wide variation between clinicians. To ensure that the information is directly transferable, clinicians have a responsibility to use repeatable measurements and assessments wherever possible. Standard scoring systems and criteria that have been developed primarily for use in the research environment are reviewed and their relevance to the clinician is discussed. In particular, the repeatability of measures is considered.     

Lymphocyte antigens in sheep

This paper describes the detection of 13 lymphocyte antigens in sheep. The results obtained from family studies are consistent with the hypothesis that at least 12 antigens are under the control of a single genetic system. The distribution of antigens in the population suggests that the system contains two loci. The 13 antigens were compared with those previously reported. Only one additional specificity was found.     

Reproductive cycles in sheep

During the last three decades, there has been remarkable progress in many aspects of ovarian biology due to advances in real-time ultrasonography, which permits non-invasive, repeated monitoring of ovarian structures in conscious and non-anaesthetised animals. This review is primarily concerned with ovarian activity, as determined by transrectal ultrasonography, and measurements of circulating concentrations of gonadotrophins and ovarian steroids during reproductive cycles in sheep. The growth of antral follicles reaching ostensibly ovulatory sizes occurs in a wave-like pattern throughout the breeding season in both prolific and non-prolific breeds of sheep. There are typically 3 or 4 waves of follicle development during the interovulatory interval. Follicular wave emergence is primarily controlled by changes in circulating concentrations of follicle-stimulating hormone (FSH) but diminished ovarian responsiveness to gonadotrophic signals may result in reduced numbers of follicular waves. In cyclic ewes, the largest ovarian follicles acquire the ability to secrete oestradiol from the day of emergence with peak oestradiol secretion occurring about the time they reach maximum diameter. The high ovulation rate in some prolific breeds may be achieved by the ovulation of follicles from the last two waves of the interovulatory interval. Prolific ewes tend to produce more but smaller corpora lutea (CL) and have lower serum concentrations of progesterone during the luteal phase of the oestrous cycle as compared to less prolific genotypes. Lastly, recent studies of the endocrine influences on ovarian function have brought into question the existence of strong follicular dominance, as seen in cattle, and provided new insights into the effects of luteal progesterone on antral follicular development in ewes.     

Economics of sheep production

The aims of this paper are to give a brief overview of world sheep production at present and to describe in detail sheep production and profitability using New Zealand as a case example. Sheep numbers have been declining throughout the world over the last five years, resulting in decreased sheep meat production and a resultant shortage of supply. There is evidence that demand in the short-term will not be met by the major exporters (New Zealand and Australia). Although sheep numbers have declined in New Zealand, production has increased dramatically, with lambing percentages increasing from 98% in 1987 to 125% in 2008 and carcass weights from 14 to 17 kg, respectively. Despite this production increase, return on capital in the farming business has been around 1% per annum. However, property values have increased by around 10% offsetting the low return on capital from farming sheep. There are a number of challenges facing New Zealand's sheep farmers, namely changing land-use patterns, climate change and greenhouse gas mitigation, all of which will potentially impact on future profitability.     

Ureteral motility in sheep

Ureteral motility was studied in twenty-five sodium pentobarbital-anaesthetized sheep. Mean frequency of the peristaltic waves was 15 per min and the range was 11-19. Frequency was the same throughout the length of the ureter. Mean contraction pressure (cm H2O) was 40 in the upper ureter, 35 in the middle ureter and 31 in the lower ureter. Mean concentration time was 1 sec and range was 0.6-1.5. Mean relaxation time was 1.1 sec and range was 0.7-1.5. Diuresis induced by rapid intravenous administration of physiologic sodium chloride solution abolished the peristaltic activity.     

Experimental chimaerism in sheep

Composite sheep embryos (N = 110) were produced by aggregation of blastomeres from 2-, 4- or 8-cell embryos. Each composite embryo consisted of equal numbers of blastomeres from 2-8 parent embryos, the total cell number ranging from one quarter of the normal cell number to 8 times the normal cell number. The embryos were embedded in agar and transferred to ligated sheep oviducts to allow development up to the early blastocyst stage. Of the 101 embryos subsequently recovered, 77 had formed normally organized blastocysts and 74 of these were transferred to 51 recipients. Thirty-eight recipients went to full term, producing a total of 53 lambs. Of the 48 lambs which survived to be blood typed at 60 days of age, 36 were judged to be chimaeric on the basis of their blood type and/or on the basis of external features. The proportion of chimaeras was larger amongst the lambs produced from composite embryos of the normal number of cells or more (25/26) than amongst lambs produced from composite embryos of less than the normal cell number (11/22).